2 * Copyright (c) 2000, 2001 Michael Smith
3 * Copyright (c) 2000 BSDi
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * $FreeBSD: src/sys/dev/acpica/acpi_timer.c,v 1.35 2004/07/22 05:42:14 njl Exp $
30 #include <sys/param.h>
32 #include <sys/kernel.h>
33 #include <sys/module.h>
34 #include <sys/sysctl.h>
35 #include <sys/systimer.h>
38 #include <machine/lock.h>
39 #include <bus/pci/pcivar.h>
46 * A timecounter based on the free-running ACPI timer.
48 * Based on the i386-only mp_clock.c by <phk@FreeBSD.ORG>.
51 /* Hooks for the ACPICA debugging infrastructure */
52 #define _COMPONENT ACPI_TIMER
53 ACPI_MODULE_NAME("TIMER")
55 static device_t acpi_timer_dev;
56 static struct resource *acpi_timer_reg;
57 static bus_space_handle_t acpi_timer_bsh;
58 static bus_space_tag_t acpi_timer_bst;
59 static sysclock_t acpi_counter_mask;
60 static sysclock_t acpi_last_counter;
62 #define ACPI_TIMER_FREQ (14318182 / 4)
64 static sysclock_t acpi_timer_get_timecount(void);
65 static sysclock_t acpi_timer_get_timecount24(void);
66 static sysclock_t acpi_timer_get_timecount_safe(void);
67 static void acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock);
69 static struct cputimer acpi_cputimer = {
70 SLIST_ENTRY_INITIALIZER,
74 acpi_timer_get_timecount_safe,
75 cputimer_default_fromhz,
76 cputimer_default_fromus,
78 cputimer_default_destruct,
83 static int acpi_timer_identify(driver_t *driver, device_t parent);
84 static int acpi_timer_probe(device_t dev);
85 static int acpi_timer_attach(device_t dev);
86 static int acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
88 static int acpi_timer_test(void);
90 static device_method_t acpi_timer_methods[] = {
91 DEVMETHOD(device_identify, acpi_timer_identify),
92 DEVMETHOD(device_probe, acpi_timer_probe),
93 DEVMETHOD(device_attach, acpi_timer_attach),
98 static driver_t acpi_timer_driver = {
104 static devclass_t acpi_timer_devclass;
105 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, NULL, NULL);
106 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
108 static inline uint32_t
109 acpi_timer_read(void)
111 return (bus_space_read_4(acpi_timer_bst, acpi_timer_bsh, 0));
115 * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
119 acpi_timer_identify(driver_t *driver, device_t parent)
126 * Just try once, do nothing if the 'acpi' bus is rescanned.
128 if (device_get_state(parent) == DS_ATTACHED)
131 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
133 if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) ||
137 if ((dev = BUS_ADD_CHILD(parent, parent, 0, "acpi_timer", 0)) == NULL) {
138 device_printf(parent, "could not add acpi_timer0\n");
141 acpi_timer_dev = dev;
143 switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
144 case ACPI_ADR_SPACE_SYSTEM_MEMORY:
145 rtype = SYS_RES_MEMORY;
147 case ACPI_ADR_SPACE_SYSTEM_IO:
148 rtype = SYS_RES_IOPORT;
154 rlen = AcpiGbl_FADT.PmTimerLength;
155 rstart = AcpiGbl_FADT.XPmTimerBlock.Address;
156 if (bus_set_resource(dev, rtype, rid, rstart, rlen, -1)) {
157 device_printf(dev, "couldn't set resource (%s 0x%lx+0x%lx)\n",
158 (rtype == SYS_RES_IOPORT) ? "port" : "mem", rstart, rlen);
165 acpi_timer_probe(device_t dev)
168 int i, j, rid, rtype;
170 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
172 if (dev != acpi_timer_dev)
175 switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
176 case ACPI_ADR_SPACE_SYSTEM_MEMORY:
177 rtype = SYS_RES_MEMORY;
179 case ACPI_ADR_SPACE_SYSTEM_IO:
180 rtype = SYS_RES_IOPORT;
186 acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
187 if (acpi_timer_reg == NULL) {
188 device_printf(dev, "couldn't allocate resource (%s 0x%lx)\n",
189 (rtype == SYS_RES_IOPORT) ? "port" : "mem",
190 (u_long)AcpiGbl_FADT.XPmTimerBlock.Address);
193 acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
194 acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
195 if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) != 0)
196 acpi_counter_mask = 0xffffffff;
198 acpi_counter_mask = 0x00ffffff;
201 * If all tests of the counter succeed, use the ACPI-fast method. If
202 * at least one failed, default to using the safe routine, which reads
203 * the timer multiple times to get a consistent value before returning.
206 for (i = 0; i < 10; i++)
207 j += acpi_timer_test();
209 if (acpi_counter_mask == 0xffffffff) {
210 acpi_cputimer.name = "ACPI-fast";
211 acpi_cputimer.count = acpi_timer_get_timecount;
213 acpi_cputimer.name = "ACPI-fast24";
214 acpi_cputimer.count = acpi_timer_get_timecount24;
217 if (acpi_counter_mask == 0xffffffff)
218 acpi_cputimer.name = "ACPI-safe";
220 acpi_cputimer.name = "ACPI-safe24";
221 acpi_cputimer.count = acpi_timer_get_timecount_safe;
224 ksprintf(desc, "%d-bit timer at 3.579545MHz",
225 (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) ? 32 : 24);
226 device_set_desc_copy(dev, desc);
228 cputimer_register(&acpi_cputimer);
229 cputimer_select(&acpi_cputimer, 0);
230 /* Release the resource, we'll allocate it again during attach. */
231 bus_release_resource(dev, rtype, rid, acpi_timer_reg);
236 acpi_timer_attach(device_t dev)
240 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
242 switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
243 case ACPI_ADR_SPACE_SYSTEM_MEMORY:
244 rtype = SYS_RES_MEMORY;
246 case ACPI_ADR_SPACE_SYSTEM_IO:
247 rtype = SYS_RES_IOPORT;
253 acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
254 if (acpi_timer_reg == NULL)
256 acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
257 acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
262 * Construct the timer. Adjust the base so the system clock does not
266 acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock)
269 timer->base = oldclock - acpi_timer_get_timecount_safe();
273 * Fetch current time value from reliable hardware.
275 * The cputimer interface requires a 32 bit return value. If the ACPI timer
276 * is only 24 bits then we have to keep track of the upper 8 bits on our
279 * XXX we could probably get away with using a per-cpu field for this and
280 * just use interrupt disablement instead of clock_lock.
283 acpi_timer_get_timecount24(void)
288 counter = acpi_timer_read();
289 if (counter < acpi_last_counter)
290 acpi_cputimer.base += 0x01000000;
291 acpi_last_counter = counter;
292 counter += acpi_cputimer.base;
298 acpi_timer_get_timecount(void)
300 return (acpi_timer_read() + acpi_cputimer.base);
304 * Fetch current time value from hardware that may not correctly
305 * latch the counter. We need to read until we have three monotonic
306 * samples and then use the middle one, otherwise we are not protected
307 * against the fact that the bits can be wrong in two directions. If
308 * we only cared about monosity, two reads would be enough.
311 acpi_timer_get_timecount_safe(void)
315 if (acpi_counter_mask != 0xffffffff)
318 u2 = acpi_timer_read();
319 u3 = acpi_timer_read();
323 u3 = acpi_timer_read();
324 } while (u1 > u2 || u2 > u3);
326 if (acpi_counter_mask != 0xffffffff) {
327 if (u2 < acpi_last_counter)
328 acpi_cputimer.base += 0x01000000;
329 acpi_last_counter = u2;
332 return (u2 + acpi_cputimer.base);
336 * Timecounter freqency adjustment interface.
339 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
344 if (acpi_cputimer.freq == 0)
346 freq = acpi_cputimer.freq;
347 error = sysctl_handle_int(oidp, &freq, 0, req);
348 if (error == 0 && req->newptr != NULL)
349 cputimer_set_frequency(&acpi_cputimer, freq);
354 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
355 0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
358 * Some ACPI timers are known or believed to suffer from implementation
359 * problems which can lead to erroneous values being read. This function
360 * tests for consistent results from the timer and returns 1 if it believes
361 * the timer is consistent, otherwise it returns 0.
363 * It appears the cause is that the counter is not latched to the PCI bus
366 * ] 20. ACPI Timer Errata
368 * ] Problem: The power management timer may return improper result when
369 * ] read. Although the timer value settles properly after incrementing,
370 * ] while incrementing there is a 3nS window every 69.8nS where the
371 * ] timer value is indeterminate (a 4.2% chance that the data will be
372 * ] incorrect when read). As a result, the ACPI free running count up
373 * ] timer specification is violated due to erroneous reads. Implication:
374 * ] System hangs due to the "inaccuracy" of the timer when used by
375 * ] software for time critical events and delays.
377 * ] Workaround: Read the register twice and compare.
378 * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
383 acpi_timer_test(void)
386 int min, max, max2, n, delta;
392 /* Test the timer with interrupts disabled to get accurate results. */
393 #if defined(__i386__)
395 #elif defined(__x86_64__)
398 #error "no read_eflags"
401 last = acpi_timer_read();
402 for (n = 0; n < 2000; n++) {
403 this = acpi_timer_read();
404 delta = acpi_TimerDelta(this, last);
408 } else if (delta > max2) {
415 #if defined(__i386__)
417 #elif defined(__x86_64__)
420 #error "no read_eflags"
424 if ((max - min > 8 || delta > 3) && vmm_guest == VMM_GUEST_NONE)
426 else if (min < 0 || max == 0 || max2 == 0)
431 kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
433 min, max, max - min);